Antisoma stock nosedived yesterday after its Novartis-partnered drug ASA404 failed to show any survival benefit in a late stage trial in patients with lung cancer, putting a huge question mark over its future.

Investor confidence in the UK firm was seriously rocked after it emerged that an interim analysis of data from the ATTRACT-1 Phase III trial in patients with previously untreated non-small cell lung cancer indicated that “there is little or no prospect of demonstrating a survival benefit”, the firm said.

By yesterday evening shares in the group had plunged 75% on the London Stock Exchange as the reality of the trial’s findings hit home; there was significant hope that ASA404 might become a blockbuster securing Antisoma a substantial future stream of royalties, but this now looks in doubt.

ASA404 is a tumour-vascular disrupting agent that selectively causes the collapse of existing blood supply to the tumour, as opposed angiogenesis inhibitors that work by preventing the formation of new blood vessels.

The drug’s novel mode of action caught the attention of Swiss drug major Novartis, which paid Antisoma an upfront fee of $75 million for rights to ASA404 back in 2007 as well as an additional $25 million on the launch of the Phase III trials in lung cancer in 2008, in the hope that the drug would become a first-in-class treatment for NSCLC.

Unsurprisingly, Antisoma’s chief executive Glyn Edwards said the company is “disappointed” by the outcome of study, “especially given the very encouraging phase II data reported in the same setting”, which indicated the drug’s significant promise for survival benefits.

The focus is now on “delivering Phase III results for our other late-stage product, AS1413,” Glyn said, for which data from late-stage clinical trials in patients with secondary acute myeloid leukaemia are expected in later this year or early 2011.